The heart of a mammal such as a human being, rodent, swine, cow, and the like, includes four valves (i.e., mitral valve, aortic valve, pulmonary valve, and tricuspid valve). The mitral valve controls the blood flow between the left atrium and the left ventricle. The tricuspid valve controls the blood flow between the right atrium and the right ventricle. The aortic valve controls the blood flow from the left ventricle to the vascular system of the body. The pulmonary valve controls the blood flow from the right ventricle to the lungs. Defective operation of any of these four valves brings about a specific medical complication. For example, a defective mitral valve may cause regurgitation (i.e., leakage between the left ventricle and the left atrium), thereby reducing the pumping efficiency of the heart, and depriving major organs of the body from oxygen and the necessary substances.
Replacement of a heart valve is a common practice in medicine. The heart valve, in this operation, is replaced by an artificial valve. An artificial valve can be either a mechanical valve or a tissue valve. A mechanical valve can be either a ball type valve or a disk type valve. Examples of the ball type valve include the Starr-Edwards valve, Magovern-Cromie Sutureless valve, and Smeloff-Sutter valve. A disk valve can be either a single leaflet disk valve (e.g., Bjork-Shiley valve, Medtronic-Hall valve, Omniscience valve), or a bi-leaflet disk valve (e.g., St. Jude valve, Carbomedics valve, Edwards-Duromedics valve).
A tissue valve can be either an animal tissue valve (i.e., xenograft or heterograft), or a human tissue valve (i.e., homograft or autograft]). A xenograft can be of valve tissue, typically porcine (i.e., pig valve tissue). Alternatively, a xenograft can be of non-valve tissue, for example bovine (i.e., cow pericardium). A homograft valve is a valve transplant from another person. An autograft is a valve moved from one position to another within the same patient, or a valve self-transplant.
Such valve replacement procedures are usually performed in an open-heart setting (i.e., cutting the sternum and opening up the rib cage, in order to gain direct access to the heart and the respective valve). As the surgeons gained more experience in this type of operation, the success rate of the surgery increased and many patients benefited from longer and relatively disease-free life.
However, due to the massive incisions that are performed in an open-heart surgery, the patient undergoes a substantially long and painful recovery period accompanied by a long term post-operation pain and morbidity. Furthermore, the patient has to follow a strict regimen following the surgery, in order to reduce future medical complications, for example due to accompanied infections.
Heart valve replacement surgery may also be performed in a closed-chest setting, by gaining access to the heart valve, either by performing a number of access holes in the chest (i.e., minimally invasive surgery), or by entering the heart chambers through the vascular system (e.g., through the right subclavian vein, or the inferior vena cava—i.e., by performing a percutaneous operation). One benefit of closed-chest surgery, is that the accompanied medical complications are much less than those of the open-heart surgery, and the patient can return to normal activity shortly following the surgery. Hence, high-risk patients, mostly morbid elderly, can benefit from percutaneous heart valve replacement surgery.
However, in a percutaneous operation, when a catheter is used, the surgeon faces the difficulty of determining the precise location of the malfunctioning heart valve, because the leaflet tissue of the malfunctioning heart valve has similar biological properties as the rest of the heart tissue. Therefore, the malfunctioning heart valve can not be clearly differentiated from the background, in an image of the heart (e.g., X-ray, computer tomography, or magnetic resonance imaging), unless the malfunctioning heart valve is calcified. A prevalent method in detecting the location of the valve, is injecting a contrast agent in the vascular system. Then a first image is acquired when the left ventricle, for example, is filled with the contrast agent, and a second image is acquired when the left atrium is filled with the contrast agent.
Since the malfunctioning valve is generally calcified, the location thereof is indicated accordingly, in each of the first and the second images. The medical staff member alternates between the first image and the second image, to estimate the approximate location of the malfunctioning heart valve. The surgeon maneuvers the artificial heart valve toward the approximate location of the malfunctioning heart valve, based on his or her visual memory.
The catheter which is used in this operation is a balloon catheter, which includes an inflatable balloon at the tip thereof. The artificial heart valve, an outer nitinol stent, and an inner platinum stent are secured to the inflatable balloon. The inner platinum stent contains the artificial heart valve. The outer nitinol stent and the inner platinum stent are secured together, along the commissures of the artificial heart valve, instead of the leaflets of the artificial heart valve. The surgeon aligns the sections of the expanded outer nitinol stent with the leaflets of the malfunctioning heart valve, by presuming that the tip of the catheter (i.e., the artificial heart valve) is located at the location of the malfunctioning heart valve, and then she inflates the inflatable balloon.
When the inflatable balloon is inflated, the sections along the leaflets of the artificial heart valve expand, while leaving the sections along the commissures, secured to the inner platinum stent. The inner platinum stent is expanded, thereby deploying the outer nitinol stent in the position of the malfunctioning heart valve. In this manner, the leaflets of the malfunctioning heart valve are sandwiched between the outer nitinol stent and inner platinum stent, and the leaflets of the malfunctioning heart valve are fixed against the side wall of the coronary ostia (i.e., the heart chamber opening). The surgeon then deflates the inflatable balloon, thereby permanently fixing in place the outer nitinol stent, the inner platinum stent, and the artificial heart valve. The medical staff member then removes the catheter from the body of the patient.
In order to fix the artificial heart valve in place, the surgeon has to arrest heart function for a very short period of time. Otherwise, if the inflatable balloon is inflated or maneuvered within the chambers of the heart, while the myocardium of the heart is continuously contracting, then the inflatable balloon will likely be sucked into the chamber. This event can severely injure the heart tissues or block the blood flow within the heart (i.e., cause ischemic heart failure). The heart function can be arrested for only a very short time (i.e., tens of seconds), otherwise, the brain and other organs of the body are deprived of oxygen, which may result in permanent damage. Therefore, it is clear that the surgeon is given a very short time, to perform the actual task of fixing in place the artificial heart valve. Alternatively, the medical staff member can employ an elongated tubular manipulator having an ejector, to eject the artificial heart valve at the location of the malfunctioning heart valve.
U.S. Pat. No. 6,899,704 B2 issued to Sterman et al., and entitled “Devices and Methods for Intracardiac Procedures”, is directed to a less-invasive surgical procedure within the heart and great vessels of the thoracic cavity. One such surgical procedure is closed-chest mitral valve replacement. A percutaneous intercostal penetration is performed in the chest of the patient (i.e., an incision through the chest wall between two adjacent ribs, in which the rib cage and sternum of the patient remain substantially intact). An endoscope is inserted though the intercostal penetration (e.g., through an access cannula or a trocar sleeve). The endoscope is manipulated to view the right side of the heart.
A video camera is mounted to the endoscope and connected with a video monitor, which provides a video image of the interior of the thoracic cavity. The patient is placed on cardiopulmonary bypass, the right lung is partially collapsed and cardiac function is arrested. Venting may be performed to maintain decompression of the left side of the heart. A surgical cutting instrument (e.g., angled scissors) and a grasping instrument (e.g., forceps) are inserted though the intercostal penetration, and used to cut through the right side of the left atrium to form an atriotomy.
A retractor is used to retract the wall of the left atrium on the anterior side of the atriotomy, exposing the mitral valve within the left atrium. A clamping device maintains the retractor in position. The mitral valve leaflets are removed using the surgical cutting instrument. The valve annulus is sized for selecting a replacement valve of the proper size. The replacement valve is mounted to an introducer. The introducer is advanced through the atriotomy, until the replacement valve is positioned against or within the valve annulus. The replacement valve may be attached to the heart, by suturing to the valve annulus. The atriotomy is then closed, all instruments are removed from the thoracic cavity, and all incisions and penetrations are closed. The lung is re-inflated, cardiac function restarted, and cardiopulmonary bypass discontinued.
U.S. Pat. No. 6,821,297 B2 issued to Snyders, and entitled “Artificial Heart Valve, Implantation Instrument and Method Therefor”, is directed to an artificial valve for repairing a damaged heart valve. The artificial valve includes a flexibly resilient external frame and a flexible valve element attached to the center of the frame. The frame includes a plurality of stenting elements, extending between opposite ends of the frame, a band extending around the frame between the stenting elements, and anchors, at each end of the stenting elements. The stenting elements and the band enable the frame to be compressed to a collapsed configuration. For repairing a damaged mitral valve, an endothoracoscopic instrument is inserted through a jugular or femoral vein.
The endothoracoscopic instrument includes a tubular holder, and a tubular manipulator attached to the holder, for manipulating the holder into position. An ejector is positioned in a hollow interior of the holder, for ejecting the artificial valve from the holder. The artificial valve frame is placed in the collapsed configuration inside the holder. A small opening is made in the chest wall of the patient, and a small incision is made in the heart. The holder end of the instrument is inserted through the opening and the incision.
The artificial valve is ejected into a position between the cusps (i.e., which separate the left atrium from the left ventricle) of the damaged mitral valve. The anchors (e.g., hooks) attach the frame of the artificial valve into position between the cusps. The instrument is withdrawn from the chest, and the opening and incision are closed. The flexible valve element opens when the fluid pressure in the left atrium is greater than the fluid pressure in the left ventricle, permitting downstream flow between the left atrium and the left ventricle. The flexible valve element closes when the fluid pressure in the left ventricle is greater than the fluid pressure in the left atrium, blocking flow reversal from the left ventricle to the left atrium.
U.S. Pat. No. 6,830,585 B1 issued to Artof et al., and entitled “Percutaneously Deliverable Heart Valve and Methods of Implantation”, is directed to a stentless prosthetic heart valve suitable for replacement of a defect or diseased human heart valve, and methods of implantation. The prosthetic valve has three leaflets secured together by sutures. Each of the leaflets has an in-flow edge, an out-flow edge, and side edges. The leaflets are secured together by sutures, forming an annulus at the in-flow edge and the commissure tissue. A plurality of tabs are mounted to the commissure tissue of the leaflets (i.e., the tissue at the commissural end point of any two leaflets). The annulus is connected to an annulus base support, which is collapsible and expandable.
The annulus base support is covered with a cloth cover, for attaching the annulus base support onto the heart tissue. During implantation, the prosthetic valve is collapsed and positioned within a delivery means (e.g., a catheter). The delivery means is introduced into the aorta area of the patient, through a percutaneous intercostal penetration of the chest or an opening of a blood vessel.
The valve is deployed from the delivery means and expanded, with the annulus base support positioned at the location of the anatomical heart valve. The distal end of the commissure tissues are secured to the aorta wall using a valve rivet. The valve rivet is inserted endoluminally to the prosthetic valve position. The rivet tip penetrates through the commissure tissue and the aorta wall. The valve rivet is pushed forward, which releases preformed wires which expand radially outwards to hold the aorta wall in place. The valve rivet is then pulled back, compressing and expanding the preformed wires, thereby securing the commissure tissue to the aorta wall.
U.S. Pat. No. 6,651,671 B1 issued to Donlon et al., and entitled “Less-Invasive Devices and Methods for Cardiac Valve Surgery”, is directed to surgical instruments for a less-invasive heart surgery, such as the repair and replacement of heart valves. One such surgery type is aortic valve replacement. The patient is placed under general anesthesia, cardiopulmonary bypass is established to support circulation, and cardioplegic arrest is induced. At least one access port is formed percutaneously in the intercostal spaces between the ribs on the right anterior side of the chest. The access port may include a trocar sleeves, or an incision in which tissue is retracted apart to create a small opening.
The pericardium is opened to expose the ascending aorta, and an incision is formed in the ascending aorta wall (i.e., an aortotomy), using thoracoscopic angled scissors. The aortotomy is retracted open (e.g., using sutures), exposing the aortic valve. The leaflets of the aortic valve are removed using the angled scissors and forceps, positioned through the access ports. Thoracoscopic rongeurs remove any calcific deposits and any remaining leaflet tissues around the inner surface of the valve annulus.
The valve annulus is sized using a valve sizing device, to determine the appropriate size for the replacement valve. The prosthetic valve (e.g., a mechanical valve) is mounted to a holder on a delivery handle. The delivery handle is advanced into the chest through an inner lumen of an access port. The prosthetic valve is positioned adjacent to the valve annulus, and released from the delivery handle. The prosthetic valve is secured to the valve annulus, such as by using sutures. The moveable leaflets of the prosthetic valve may be tested for proper functioning using a probe. The aortotomy is closed, cardiac function is resumed, cardiopulmonary bypass is disabled, all incisions are closed, and all instruments are removed from the patient.
U.S. Pat. No. 6,402,780 B2 issued to Williamson, I V et al., and entitled “Means and Method of Replacing a Heart Valve in a Minimally Invasive Manner”, is directed to a device and method of fastening an aortic valve prosthesis into living tissue. A flexible and sutureless sewing cuff is attached to the aortic annulus using a fastener delivery tool. The fastener delivery tool includes an operating handle and a fastener deployment knob on one end, and an operating head on the other end. The operating head includes a housing containing fasteners (e.g., staples).
The cuff is stretched over the operating head. The fastener delivery tool is inserted into the patient via an incision located in the thorax. The fastener delivery tool positions the cuff adjacent to the aortic annulus tissue, and holds the cuff securely against the tissue throughout the fastener setting procedure. The tool drives a fastener through the cuff and the tissue, and then folds over the fastener legs, thereby securely attaching the cuff to the tissue. A series of fasteners are likewise arranged throughout the entire circumference of the cuff (e.g., spaced in a staggered and uniform pattern).
The fastener delivery tool is removed from the heart, and the valve prosthesis is inserted into the aortic lumen and positioned inside the cuff. The valve prosthesis is attached to the cuff using drawstrings, which extend outside the body of the patient. Indicating means (e.g., a garter spring) located in the lower section of the cuff, holds the valve in place, and provides a signal to the surgeon when the valve body is properly seated in the cuff before activating the drawstrings. The indicating means later provides a tactile signal to the surgeon indicating that the valve is securely attached to the cuff.
US Patent Publication No. 20020049375 entitled “Method and Apparatus for Real Time Quantitative Three-Dimensional Image Reconstruction of a Moving Organ and Intra-Body Navigation”, is directed to a system for displaying an image of a lumen of a patient into which a surgical catheter is inserted, while taking into account the movements of the lumen caused by the heart beats of the patient. The system includes the surgical catheter, an imaging catheter, an imaging system, a medical positioning system (MPS), a transmitter, a body MPS sensor, a processor, a plurality of electrocardiogram (ECG) electrodes, an ECG monitor, a database, and a display. The surgical catheter includes a catheter MPS sensor located at a tip thereof. The imaging catheter includes an imaging MPS sensor and an image detector, both located at a tip of the imaging catheter.
The ECG electrodes are attached to the body of the patient and to the ECG monitor. The body MPS sensor is attached to the body of the patient and to the MPS. The processor is coupled with the imaging system, the MPS, the ECG monitor, the database and with the display. The MPS is coupled with the transmitter. During the scanning procedure the MPS is coupled with the imaging MPS sensor. During the surgical procedure the MPS is coupled with the catheter MPS sensor. The imaging system is coupled with the image detector. The imaging MPS sensor and the catheter MPS sensor send a signal respective of the position and orientation of the tip of the imaging catheter and the surgical catheter, respectively, to the MPS.
During the scanning procedure, an operator inserts the imaging catheter into the lumen and advances it therein, while the image detector scans the inner wall of the lumen and transmits detected two-dimensional images to the imaging system. The processor reconstructs a plurality of three-dimensional images according to the two-dimensional images and according to the coordinates of the tip of the imaging catheter determined by the MPS, while the processor associates each three-dimensional image with a respective activity state of the heart of the patient.
During the surgical procedure, the operator inserts the surgical catheter into the lumen and the catheter MPS sensor sends a location signal respective of the position and orientation of the tip of the surgical catheter to the MPS. As the operator moves the surgical catheter within the lumen, the processor determines a sequence of three-dimensional images of the lumen by retrieving data from the database, and according to the current position and orientation of the tip of the surgical catheter and the current activity state of the heart of the patient. The display displays the three-dimensional images in sequence, according to a video signal received from the processor.